By Andy Flick
Associate Professor of Psychology and Human Development Laura Novick, and graduate student Joanna (Jingyi) Liu, published a paper highlighting the importance of intentionally and thoughtfully designed figures to explain evolutionary relationships and overcome preconceived misconceptions.
The work was inspired, in part, by a common misconception that was rampant at the beginning of the COVID-19 pandemic. Many people assumed the SARS-CoV-2 virus was similar to the flu virus, as most of the symptoms overlapped. However, a phylogenetic tree showed that the two viruses are in fact only distantly related.
Liu and Novick hypothesized that changes to the layout or content of an evolutionary tree might be enough to help students reason based on evolutionary evidence rather than their prior misconceptions. For example, it is not uncommon for people to think that whales are more closely related to manatees than to bison, when the opposite is true. The misconception is reasonable enough, given that manatees and whales both look similar and live in the same type of environment.
The human brain has a strong tendency to associate like items. Perceptual similarity is one basis for grouping items. The Gestalt principles of perceptual grouping describe a suite of criteria, including perceptual similarity, that our brains use to extrapolate relationships among objects.
Novick explained, using the figure below, “The first line is an ungrouped set of six squares. We see six individual squares. But in the second row, because some squares are closer to each other than to other squares, we automatically see that row as consisting of three groups of two squares each. We don’t have to do any analyzing or reasoning; we just automatically see this grouping of the squares.”
In the bottom row of the figure above, we see three groups based on the lines that connect them. This perceived grouping is important when creating evolutionary trees (also known as cladograms). Specifically, this is known as the Gestalt principle of perceptual grouping based on connectedness.
Liu and Novick showed Vanderbilt undergraduates cladograms that used two different branching structures for depicting relationships among types of living things. These cladograms were called either weakly contradictory (easier to form the misconception) or strongly contradictory (harder to form the misconception), for the way in which they depicted relationships between species that are commonly misconceived as close relatives. They found that students were less likely to make an inappropriate scientific inference (e.g., that whales have the same type of placenta as manatees) when the cladogram strongly contradicted their misconception. This can mean the designers of the cladogram should use one or two different species to create automatic perceptual groupings that reinforce the correct interpretation. Understanding when a cladogram contains a common evolutionary misconception and actively creating a diagram to correct that misconception can help students reason the correct information more easily or more often.
“Even though the perceptual grouping of the tree branches is irrelevant to evaluating evolutionary relatedness, research shows that it can either facilitate or hinder correct interpretation of the relationships among the taxa included in the tree,” Novick said. “This, in turn, will affect the likelihood of students making appropriate scientific inferences based on the information provided.”
A major takeaway from this work is that evolutionary biologists need to keep non-biological concepts like the Gestalt principles of perceptual grouping in mind when designing cladograms.
In the online version of the manuscript, Appendix A has figures that show how to create cladograms to contradict misconceptions. For example, mushrooms are more closely related to animals than they are to plants. In the figure for “the mushroom misconception,” the left panel and the right panel both correctly show that mushrooms are more closely related to animals. However, the right panel clearly shows plants as an outgroup – or more distantly related to mushrooms – rather than animals.
Liu commented that this project helped her correct some of the misconceptions she had about evolutionary relationships. She said that the one that sticks out is the erroneous belief that shrimp are more closely related to fish than to insects. Liu joked, “Another favorite is that shrimp are more closely related to insects than to trout and sea urchins; it’s a great – though maybe not too appetizing – conversation starter when I’m at a party that serves seafood!”
Citation: Liu, Jingyi, and Laura R. Novick. Perceptual grouping affects students’ propensity to make inferences consistent with their misconceptions. Journal of Experimental Psychology: Applied (2022).
This article was originally published at Evolution@Vanderbilt.